linux-kernel - [PATCH 4.16 17/72] perf: Remove superfluous allocation error check

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Message-Id: <20180514064823.770904806@linuxfoundation.org>
Date:   Mon, 14 May 2018 08:48:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <andi@...stfloor.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        syzkaller-bugs@...glegroups.com, x86@...nel.org
Subject: [PATCH 4.16 17/72] perf: Remove superfluous allocation error check

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Olsa <jolsa@...nel.org>

commit bfb3d7b8b906b66551424d7636182126e1d134c8 upstream.

If the get_callchain_buffers fails to allocate the buffer it will
decrease the nr_callchain_events right away.

There's no point of checking the allocation error for
nr_callchain_events > 1. Removing that check.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: syzkaller-bugs@...glegroups.com
Cc: x86@...nel.org
Link: http://lkml.kernel.org/r/20180415092352.12403-3-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/events/callchain.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -131,14 +131,8 @@ int get_callchain_buffers(int event_max_
 		goto exit;
 	}

-	if (count > 1) {
-		/* If the allocation failed, give up */
-		if (!callchain_cpus_entries)
-			err = -ENOMEM;
-		goto exit;
-	}
-
-	err = alloc_callchain_buffers();
+	if (count == 1)
+		err = alloc_callchain_buffers();
 exit:
 	if (err)
 		atomic_dec(&nr_callchain_events);